textproduct: Albany

SYNOPSIS

Lake effect snow will set up across the Adirondacks late this afternoon into tonight before dropping southward into the Mohawk Valley and Northern Catskills on Friday. Several inches of accumulation is expected where the band sets up for an extended period of time. Drier weather returns on Saturday as high pressure returns before another system brings rain and snow on Sunday.

SHORT TERM /THROUGH SATURDAY/

Key Messages:

- A period of lake effect snow is expected later today through Friday across portions of the Adirondacks, Mohawk Valley and northern Catskills. Snowfall amounts of 6 to 12 inches are expected in the most persistent lake effect bands.

- A Lake Effect Snow Warning remains in effect for Herkimer and Hamilton Counties with Winter Weather Advisories for Fulton, Montgomery, and Schoharie Counties. - Wind gusts between 30 and 40 mph, especially on Friday, could lead to areas of blowing and drifting snow.

Discussion:

Update as of 940 am EST...Happy Thanksgiving!!! Clouds quickly increased across the forecast area in the cyclonic flow with another disturbance/sfc trough approaching west-central NY. This update is to make it cloudy/mostly cloudy across eastern NY and western New England with brisk winds and scattered snow showers/flurries especially west of the Hudson River Valley. Max temps will be in the 30s to lower 40s (Capital District/Mid Hudson Valley) with upper 20s over the higher terrain.

Previous Discussion...

A nearly vertically-stacked low pressure system will slowly lift northward into Quebec through tomorrow as large scale troughing builds over the region. The return of colder air aloft will aid in a period of lake effect snow through the remainder of the week. The lake effect bands have already begun to develop within the current southwesterly flow, which is mainly to the west of our county warning area. This southwesterly flow will continue through much of Thanksgiving Day which will lead to most areas seeing dry weather. The exception would be whether any fragments of the band off Lake Erie extend as far inland into parts of the Mohawk Valley and Upper Hudson Valley. However, temperatures above freezing and the light nature of the precipitation will lead to little or no snow accumulation. The lake effect band off Ontario will remain well north of Route 28 in northern Herkimer County through this afternoon. Outside of the lake effect, it will be a breezy and cooler day with highs in the lower 30s to lower 40s.

Tonight, the passage of an upper level shortwave will result in flow shifting more west to northwesterly. This will slowly drop the band southward toward the Mohawk Valley. A blend of the latest CAMs suggest the band could reach the Mohawk Valley and Thruway corridor by daybreak Friday (4-7am). There will likely be some weakening and fluctuations in the band location Friday morning due to the passage of the trough and increasing low- level directional shear. However, the shear will weaken with increasing lake induced instability and a more organized multi lake connection (mostly with Georgian Bay) for a more intense band by Friday afternoon into Friday evening. While confidence remains lower on band placement on Friday, all scenarios from the band setting up right along the Thruway or just south remain on the table. The latest CAMs have, however, trended slightly farther north with the band placement near the Thruway corridor during its most intense time. Where this band does set up, 1 to 2 inch per hour rates can occur with near whiteout conditions possible at times due to the gusty winds and high snowfall rates. This could impact Thanksgiving holiday travel, especially if the band sets up right over the Thruway. This band will extend well inland with some light accumulations possible even into parts of the Hudson Valley and into western New England, including the Capital District. Outside of the lake effect, upslope snow showers are expected across southern Vermont into western Massachusetts with some light accumulations, especially in the higher elevations, as well as additional light accumulations for the Adirondacks. The upper trough will depart the region Friday night into early Saturday as high pressure builds in from the west. This will result in gradual weakening of the band with the band diminishing by Saturday morning.

Lake Effect Snow Warnings and Winter Weather Advisories remain as is with this forecast cycle. 6 to 12 inches of snow still seems likely in the most persistent bands within the warning areas. However, will have to monitor where the band sets up on Friday which may result in the need for upgrades for some locations east of southern Herkimer County with some CAMs suggesting localized areas of 6 or more inches within the band.

High temperatures Friday will only reach the 30s in most areas and the upper 20s in the higher elevations. Wind gusts on the order of 30 to 40 mph will make it feel even colder. Saturday will feature more sun and less wind but it will remain chilly with highs once again in the upper 20s to upper 30s, except lower 40s in the mid-Hudson Valley.

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/

After a drier Saturday, the next low pressure system will cross the region on Sunday. The primary low will track northeastward across the Great Lakes. Some cold air will likely linger early on Sunday for a period of snow, then warmer air returns changing valley areas to rain and a rain/snow mix for the higher elevations. Some light snow accumulations could occur on Sunday, especially for the higher terrain. Temperatures Sunday rebound to the mid-30s to mid-40s.

The system's cold front crosses the region Sunday night with colder air returning once again. Another brief lake effect response could occur on Monday but looks to be short lived with lighter accumulations compared to later this week as high pressure quickly builds overhead.

Attention next turns to Tuesday-Wednesday of next week as long range models are hinting at a southern stream shortwave developing a surface low near the Gulf Coast and intensifies as it tracks northeastward near or off the East Coast. Spread is large on the overall track of this system. If a track is closer to the coast, a widespread precipitation event could occur across the area. A track farther off the coast could result in less or no precipitation. At this time, thermal profiles would support mostly snow should precipitation occur. Trends on this event will be monitored over the next several days.

AVIATION /15Z THURSDAY THROUGH MONDAY/

Our region is situated behind a departing surface cold front, but ahead of an approaching upper level trough. With cooler air moving aloft, lake effect snow bands have been developing off the eastern Great Lakes. With the flow primarily southwest, these bands and associated cloud cover has remained west and northwest of the region. Skies will start off fairly clear for most sites with just few-sct cu/stratocu around 5-7 kft, although a band of high clouds is located near KPOU as well.

As the flow shifts and becomes more westerly during the day today, there will be more clouds cover across our area by the mid to late morning hours and into the afternoon, with bkn cigs around 3500-5000 ft. Any of the lake effect precip should remain west of the area during the day today. West to southwest winds will be 10 to 15 kts, with some higher gusts, especially at KALB and KPSF. These winds will diminish somewhat for tonight, but continue to stay breezy. Some additional bkn stratocu clouds around thanks to the lake effect activity will be around through the overnight hours, especially towards daybreak, when a stray flurry or snow shower might be close to KGFL or KALB.

Outlook... Friday Night: Moderate Operational Impact. Breezy. Chance of SHSN. Saturday: Low Operational Impact. Breezy. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: High Operational Impact. Definite RA...SN. Sunday Night: Moderate Operational Impact. Likely SHRA...SHSN...RA. Monday: No Operational Impact. NO SIG WX. Monday Night: Low Operational Impact. Slight Chance of SN. Tuesday: Moderate Operational Impact. Chance of SN.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Lake Effect Snow Warning from 4 PM this afternoon to 1 AM EST Saturday for NYZ032-033. Lake Effect Snow Warning from 1 AM Friday to 7 AM EST Saturday for NYZ038. Winter Weather Advisory from 1 AM Friday to 7 AM EST Saturday for NYZ039-040-047-082. MA...None. VT...None.